Circulating pump

ABSTRACT

A circulating pump includes a conveying element for conveying a conveyed liquid, and an electric motor which has a stator, a rotor, and a gap therebetween, wherein the rotor includes a shaft rotatable about a rotation axis and to which the conveying element is rotationally fixed, and the shaft is mounted to a radial slide bearing having a lubrication region configured to be liquid-lubricated with the conveyed liquid. The circulating pump includes a sealing device which inhibits fluid communication between the lubrication region and the gap located between the stator and the rotor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation patent application of international application number PCT/EP2014/066043 filed on Jul. 25, 2014 and claims the benefit of German application No. 10 2013 107 986.5 of Jul. 25, 2013, which are incorporated herein by reference in their entirety and for all purposes.

FIELD OF THE INVENTION

The invention relates to a circulating pump comprising a conveying element for conveying a conveyed liquid, and an electric motor which has a stator and a rotor, a gap being formed therebetween, wherein the rotor comprises a shaft which is rotatable about a rotation axis and to which the conveying element is connected so as to be rotationally fixed thereto, and wherein the circulating pump for mounting the shaft has a radial slide bearing which in a lubrication region is liquid-lubricated using the conveyed liquid.

BACKGROUND OF THE INVENTION

A circulating pump of this type is used in heating installations, for example, wherein the conveyed liquid may be water, in particular. The conveyed liquid is conveyed by means of the conveying element, for example an impeller which is connected so as to be rotationally fixed to the shaft. The shaft in relation to the rotation axis is radially mounted by means of a slide bearing which comprises bearing elements made of graphite, for example, on account of which a compact construction of the circulating pump may be achieved. In order to reduce wear and to dissipate heat, the slide bearing is liquid-lubricated, wherein for the purpose of a simplified design of the circulating pump lubrication is performed by way of the conveyed liquid.

Conventional circulating pumps have an electric motor for the drive, in which the rotor comprising the shaft with respect to the stator is rotatable about the rotation axis. For example in the case of asynchronous motors, the rotor usually rotates so as to be free of contact with the stator, to which end a gap is formed so as to be located between the rotor and the stator. The gap is penetrated by the magnetic fields which are generated by the stator for driving the rotor, and may be filled with liquid, in particular with the conveyed liquid. Circulating pumps of the above general type exist for this purpose, in which circulating pumps the lubrication region is in fluid communication with the gap. It is desirable for high efficiency of the circulating pump that the gap located between the stator and the rotor is formed so as to be as narrow as possible.

An object underlying the present invention is to provide a circulating pump of the type mentioned at the outset, by way of which reliable operation is enabled.

SUMMARY OF THE INVENTION

In an aspect of the invention, a circulating pump comprises a conveying element for conveying a conveyed liquid and an electric motor which has a stator and a rotor, a gap being formed therebetween, wherein the rotor comprises a shaft which is rotatable about a rotation axis and to which the conveying element is connected so as to be rotationally fixed thereto, and wherein the circulating pump for mounting the shaft has a radial slide bearing which in a lubrication region is liquid-lubricated using the conveyed liquid. The circulating pump comprises a sealing device which inhibits fluid communication between the lubrication region and the gap located between the stator and the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following description may be better understood in conjunction with the drawing figures, of which:

FIG. 1: shows a longitudinal sectional view of a first preferred exemplary embodiment of a circulating pump in accordance with the invention;

FIG. 2: shows an enlarged illustration of detail A in FIG. 1;

FIG. 3: shows an illustration corresponding to FIG. 2 of a further exemplary embodiment of a circulating pump in accordance with the invention;

FIG. 4: shows an illustration corresponding to FIG. 2 of a further exemplary embodiment of a circulating pump in accordance with the invention;

FIG. 5: shows a longitudinal sectional view of a further preferred exemplary embodiment of a circulating pump in accordance with the invention;

FIG. 6: shows an illustration corresponding to FIG. 2 of a further exemplary embodiment of a circulating pump in accordance with the invention; and

FIG. 7: shows a longitudinal sectional view of a further preferred exemplary embodiment of a circulating pump in accordance with the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

The invention relates to a circulating pump comprising a conveying element for conveying a conveyed liquid, and an electric motor which has a stator and a rotor, a gap being formed therebetween, wherein the rotor comprises a shaft which is rotatable about a rotation axis and to which the conveying element is connected so as to be rotationally fixed thereto, and wherein the circulating pump for mounting the shaft has a radial slide bearing which in a lubrication region is liquid-lubricated using the conveyed liquid. The circulating pump comprises a sealing device which inhibits fluid communication between the lubrication region and the gap located between the stator and the rotor.

In the case of the circulating pump in accordance with the invention, directed lubrication of the slide bearing on the lubrication region may be ensured by using the conveyed liquid. This enables wear of the slide bearing to be effectively reduced and frictional heat between the slide bearing and the shaft to be dissipated by means of the conveyed liquid. Moreover, a sealing device by way of which fluid communication between the lubrication region and the gap located between the stator and the rotor may be inhibited or at least largely inhibited is provided in the circulating pump in accordance with the invention. This allows the formation of a fluid flow of the conveyed liquid between the lubrication region and the gap located between the stator and the rotor to be prevented. The amount of conveyed liquid which penetrates the gap may be reduced on account thereof. This proves particularly advantageous in the case of electric motors which for achieving high efficiency have a narrowly configured gap and moreover operate using intense and alternating magnetic fields. These in particular include electrically commutated electric motors, so that especially a circulating pump in accordance with the invention having an electrically commutated electric motor may be operated in a more reliable manner by way of the teaching in accordance with the invention. On account of the reduction of the volumetric flow of conveyed liquid through the gap, the probability of magnetic particles entrained in the conveyed liquid being deposited on the rotor or the stator is reduced in particular in the case of the presence of even narrow gaps located between the stator and the rotor. An accumulation of this type of magnetic particles results in undesirable friction between the rotor and the stator. The friction may lead to a drop in efficiency, to generation of noise and heat, to undesirable wear, and even to failure of the circulating pump. These disadvantages which can be traced back to the accumulation of magnetic particles in the gap located between the stator and the rotor may be thus largely avoided in the circulating pump in accordance with the invention.

It is favorable for the circulating pump to comprise a fluid guide which, for supplying, transmitting, or discharging conveyed liquid into, through, or from the lubrication region has at least one fluid channel or fluid duct which is perfusible by conveyed liquid. This allows a flow of conveyed liquid in a lubrication region to be provided in a constructively simple manner.

The fluid guide may be implemented in a simple manner in that it bypasses the gap located between the stator and the rotor.

The fluid guide is routed past the gap located between the stator and the rotor, for example.

Preferably at least one entry opening for conveyed liquid into a fluid channel and at least one exit opening for conveyed liquid out of a fluid channel are provided. It may be provided, for example, that at least one fluid channel by way of an entry opening or by way of an exit opening is in fluid communication with a conveying space of the circulating pump in which the conveying element is disposed.

It is favorably provided that a fluid channel by way of at least one entry opening is in fluid communication with a pressurized side or an intake side of the circulating pump and/or that a fluid channel by way of at least one exit opening is in fluid communication with a pressurized side or an intake side of the circulating pump.

Advantageously, at least one fluid channel for the conveyed liquid is disposed at the lubrication region and/or the circulating pump preferably comprises a fluid guide having at least one fluid channel for conveyed liquid.

Compact construction of the circulating pump may be achieved when at least one fluid channel is formed in the slide bearing or in the shaft. This enables savings in terms of separate fluid channels so that a design of the circulating pump which is of simple construction may also be achieved. It may also be provided that a plurality of fluid channels are formed in each case in the slide bearing and/or in the shaft.

It is also conceivable for at least one fluid channel to be formed on the slide bearing or on the shaft.

A bearing gap which is disposed between the slide bearing and the shaft may form a fluid channel.

In one implementation of the circulating pump of simple construction it is favorable if at least one fluid channel is disposed between the slide bearing and the shaft. A recess such as a groove-shaped recess for forming a fluid channel between the shaft and the slide bearing may be disposed on that side of the slide bearing that faces the shaft, for example. Conveyed liquid may be guided through the recess in order for both the shaft as well as the slide bearing to be wetted and for effective fluid lubrication to be provided.

It is advantageous for at least one entry opening or exit opening through which the conveyed liquid enters into the shaft or exits therefrom, respectively, to be formed on the shaft. In this way it is conceivable, for example, that an entry opening for conveyed liquid into a fluid channel which is formed in the shaft is provided on the lubrication region, the other end of said fluid channel opening by way of an exit opening into the intake side or into the pressurized side of the circulating pump. In this manner, conveyed liquid may be discharged from the lubrication region and supplied to the intake side or the pressurized side of the circulating pump, respectively.

The at least one entry opening or exit opening may be a radial or axial opening through which conveyed liquid may enter into the shaft or exit therefrom axially or radially with respect to the rotation axis, respectively.

In a corresponding manner it may be provided that there is formed on the friction bearing at least one entry opening or exit opening through which the conveyed liquid may enter into the slide bearing or exit therefrom, respectively. The at least one entry opening or exit opening may be a radial or an axial opening.

Preferably, at least one fluid channel runs axially with respect to the rotation axis. It is provided, for example, that one or more axially extending fluid channels are provided in the lubrication region in particular between the slide bearing and the shaft. It is furthermore possible for one or more axial fluid channels to be provided in the shaft in order to discharge conveyed liquid from the lubrication region or to supply it thereto. Conveyed liquid may enter into the shaft or exit therefrom, respectively, by way of one or more exit openings. This enables fluid guidance which is of simple construction, for example.

Advantageously, at least one fluid channel or duct is formed as an annular channel or duct, or as a partial annular channel or duct in the circumferential direction of the rotation axis. This enables conveyed liquid to be distributed on the lubrication region in particular in the circumferential direction of the shaft and effective fluid lubrication between the slide bearing and the shaft to be provided. The annular channel or partial annular channel may be formed in particular between the slide bearing and the shaft.

It has proven favorable for at least one fluid channel to be formed as a radial channel or duct with respect to the rotation axis. At least one and preferably a plurality of radial channels are formed on an axial bearing of the circulating pump, for example, on which axial bearing the rotor may be supported against movement which is axial to the stator. Support elements, for example in the form of webs, may be disposed in the circumferential direction of the rotation axis between the radial fluid channels. The axial bearing may be supported by means of the support elements, in particular on the slide bearing. On account thereof, fluid lubrication between the axial bearing and the slide bearing is also enabled by way of the conveyed liquid in the radial fluid channels. A sealing element of the sealing device, which is preferably comprised or formed by the axial bearing, may be disposed on the axial bearing so as to be radially outward of the fluid channels.

Favorably, in at least one fluid channel is disposed a filter element for filtering the conveyed liquid. The filter element is preferably disposed in a fluid channel which with respect to the flow direction of the conveyed liquid of the fluid guide is disposed upstream of the lubrication region. On account thereof, particles which are present in the conveyed liquid may be filtered out of the conveyed liquid prior to the latter entering the lubrication region, and the former do not compromise the fluid lubrication. Damage to the slide bearing and/or to the axial bearing by way of particles entering the lubrication region may be avoided on account thereof.

The at least one filter element is held in a force-locking and/or positively-locking manner in the at least one fluid channel, for example. The filter element is press-fitted in the fluid channel, for example. The filter element may in particular be a sinter filter.

It is advantageous for at least one fluid channel to be disposed on the sealing device, wherein the sealing device is favorably positioned on the slide bearing. For example, the sealing device may be disposed so as to be axially beside the slide bearing, so that axial sealing of the lubrication region may be ensured, as will be discussed subsequently. A fluid channel may be formed on the sealing device, especially in the case of a sealing device which is in contact with the slide bearing. For example, at least one radial fluid channel or an annular channel or a partial annular channel is provided.

In one implementation of the circulating pump which is of simple construction the slide bearing preferably surrounds the shaft in an annular manner in the circumferential direction of the rotation axis.

The circulating pump preferably comprises an axial bearing for supporting the rotor against axial movement relative to the stator and which is caused in particular by impeller thrust. On account thereof, it may be ensured that the rotor maintains a nominal position in relation to the stator, so as to guarantee reliable functioning of the circulating pump. “Rotor lift” as may arise in the case of the previous circulating pumps especially at high rotational speeds of the conveying element (“impeller thrust”) may be avoided on account thereof.

Preferably, the axial bearing is axially supported on the slide bearing. On account thereof, a compact construction of the circulating pump may be achieved, for example. The axial bearing and the slide bearing may comprise interacting support elements and may in particular abut one another in a planar manner.

Preferably, at least one fluid channel is disposed on the axial bearing, for example a fluid channel of the fluid guide. This enables the lubrication region to be also disposed on the axial bearing and, on account thereof, fluid lubrication to be achieved at the axial bearing. For example, the axial bearing is lubricated in relation to the slide bearing on which the former may be axially supported.

It is favorable for the axial bearing to be connected so as to be rotationally fixed to the shaft. On account thereof, a supporting force for supporting the rotor may be effectively introduced to the shaft which is comprised by the rotor.

The axial bearing is favorably configured in an annular or disk-like manner and surrounds the shaft in the circumferential direction of the rotation axis.

The slide bearing is preferably disposed between the axial bearing and the conveying element. It has been demonstrated in practice that a compact construction of the circulating pump may be achieved on account thereof.

Advantageously and especially in the case of the last-mentioned advantageous embodiment of the circulating pump, a sealing element of the sealing device is disposed on the axial bearing. This provides the potential for axially and/or radially sealing the lubrication region by way of the sealing element, for example, and at the same time of enabling the rotor to be supported on the slide bearing by way of the axial bearing.

It is favorable for a sealing element of the sealing device to be axially positioned between the axial bearing and the slide bearing.

It is favorably provided that the axial bearing forms an axial support element for a sealing element of the sealing device. The axial bearing and the sealing element may form interacting support elements, in particular support faces which abut one another. It may be provided that the axial bearing is axially supported on the sealing element which in turn may be supported on the slide bearing and enables axial and/or radial sealing of the lubrication region.

Preferably, a sealing element of the sealing device is formed so as to be integral with the axial bearing. This may especially be understood as the axial bearing comprising or forming a sealing element of the sealing device. This enables a configuration of the circulating pump which is of simple construction.

In particular in the case of an integral construction of the sealing element, the axial bearing may be made from hard metal such as cemented or sintered carbide, for example. It is also conceivable for the axial bearing to be made from a ceramics material, for example of aluminum-oxide or carbon silicide or of carbon (carbon graphite).

In other types of advantageous embodiments of the circulating pump in accordance with the invention a sealing element of the sealing device is favorably formed so as to be separate from the axial bearing.

It is favorably provided that a sealing element of the sealing device is connected to the axial bearing. For example, the sealing element abuts on the axial bearing in a planar manner, wherein said sealing element is preferably disposed between the axial bearing and the slide bearing.

The sealing element may especially be connected so as to be rotationally fixed to the axial bearing.

It has proven advantageous for a sealing element of the sealing device to at least in portions surround the axial bearing in the circumferential direction of the rotation axis. The sealing element may be configured in a band-like or annular manner for example, such as an O-ring which is disposed on the external circumference of the axial bearing.

In another type of advantageous embodiment of the circulating pump in accordance with the invention the sealing device is preferably disposed on that side of the axial bearing that is opposite the slide bearing. In particular, this may be understood as the slide bearing and the sealing device being positioned so as to be on axially opposite sides of the axial bearing. Conveyed liquid may flow around the axial bearing and enable fluid lubrication with respect to the slide bearing, for example. The sealing device may be disposed on the opposite side, so as to seal the lubrication region.

It has proven to be advantageous for the sealing device to comprise or form a mechanical seal having a sliding ring which is rotationally fixed in relation to the stator, and having a counter ring which is connected so as to be rotationally fixed to the shaft. For example, the sliding ring is held so as to be rotationally fixed to the separator which will be mentioned subsequently, which is held so as to be rotationally fixed to the housing of the circulating pump and thus so as to be rotationally fixed with respect to the stator. The sliding ring and the counter ring are interacting sealing elements of the sealing device.

In an implementation of the circulating pump which is of simple construction it is favorable for the sliding ring to be formed by the slide bearing and for the counter ring to be formed by an axial bearing of the circulating pump. On account thereof, separate sealing elements which are distinct from the slide bearing and from the axial bearing may be dispensed with, and the circulating pump by way of simplification of construction is imparted a compact design.

Favorably, the sliding ring and the counter ring are mutually biased towards each other by a biasing element. On account thereof, reliable sealing of the lubrication region may be ensured. The biasing element is an elastic element, for example a corrugated spring or a pack of corrugated or ondular springs by way of which the sliding ring is supported. For example the sliding ring is supported on the separator which will be mentioned subsequently or on a supporting element connected thereto so as to be rotationally fixed.

Preferably, a sealing element of the sealing device is configured in an annular or disk-like manner and is disposed in a plane perpendicular to the rotation axis. For example, a sealing element which is integrally formed with the axial bearing or a sealing element which is connected to the axial bearing is annular or disk-like and is disposed in a plane perpendicular to the rotation axis.

It may be provided that the sealing device has precisely one sealing element.

It is favorable for the circulating pump to have a separator which separates the lubrication region from the gap located between the stator and the rotor, wherein the separator is at least in portions disposed between the shaft and the gap in the radial direction with respect to the rotation axis. For example, the separator element may at least in portions be in the form of a sleeve and aligned so as to be coaxial with the shaft, surrounding the shaft and in turn be surrounded by the gap.

It is favorable for the separator to comprise or form a cover which in relation to the gap located between the stator and the rotor covers a conveying space of the circulating pump in which the conveying element is disposed. On account thereof, it may be largely avoided that conveyed liquid enters into the gap from the conveying space. A fluid flow which may instigate deposits of magnetic particles in the gap may be largely avoided on account thereof. The cover is favorably fluid tight or substantially fluid tight.

The slide bearing is preferably held on the separator. This allows the circulating pump to be simplified in terms of construction. In particular, the slide bearing is held on the separator so as to be radially inward and surrounds the shaft in the circumferential direction of the rotation axis.

The separator is preferably rotationally fixed with respect to the stator, on account of which a simplification of the circulating pump in terms of construction may likewise be achieved.

It may be provided in general that a mounting of the slide bearing, by way of which mounting the slide bearing is otherwise mounted to the circulating pump, is rotationally fixed with respect to the stator.

Preferably, a rotor space which is sealed by the sealing device in relation to the lubrication region adjoins the lubrication region in the axial direction. Sealing need not necessarily be perfect. It may thus be permissible for conveyed liquid to enter into the rotor space so that the rotor space is gradually filled with liquid and/or so that liquid from the rotor space may make its way into the lubrication region. In particular, the volumetric flow between the rotor space and the lubrication region is negligible in relation to the volumetric flow through a fluid guide.

In the case of the last-mentioned advantageous embodiment of the circulating pump in accordance with the invention it may be provided that the rotor space is in fluid communication with the gap located between the stator and the rotor. This allows for conveyed liquid to be kept in the rotor space and in the gap located between the stator and the rotor, but for an accumulation of magnetic particles in the gap to be largely avoided at the same time. However heat dissipation in the gap can be ensured by keeping the conveyed liquid ready.

In order for a compact construction of the circulating pump to be achieved, it is favorable for the conveying element and the slide bearing to be disposed in the axial direction on the same side of the sealing device that is opposite to the side on which the rotor space is disposed.

In particular, the rotor space and the lubrication region are disposed on mutually opposite sides of the axial bearing.

It is advantageous for the shaft to axially engage through the sealing device, and for the rotor to have a magnet mounting which in the rotor space is connected so as to be rotationally fixed to the shaft, at least one permanent magnet of the electric motor being held on said magnet mounting. This allows a compact construction of the circulating pump in which the conveying element, the slide bearing, the sealing device, the axial bearing and the magnet mounting in relation to the rotation axis are disposed on the shaft.

It may be provided that the rotor space by way of the rotor is in fluid communication with a conveying space of the circulating pump, in which the conveying element is disposed. For example, fluid communication is performed through the shaft in which for this purpose at least one fluid channel may be formed. Entry of conveyed liquid into the rotor space may also be enabled in this embodiment, wherein here too, the volumetric flow of conveyed liquid into the rotor space is negligible in relation to the volumetric flow based on a fluid guide.

It is favorable for the circulating pump to comprise a pumping device by way of which conveyed liquid is conveyable through the lubrication region. A fluid flow for improved supply and discharge of conveyed liquid may be ensured by way of the pumping device, which is to a certain degree a “lubricating pump”. The pumping device is a friction pump, for example. The pumping device is preferably drivable by the rotor.

The amount of conveyed liquid which is conveyed by way of the pumping device is preferably independent or substantially independent of the operating point of the circulating pump. This may presently be understood in particular as the amount of conveyed liquid being independent or substantially independent of the differential pressure of the circulating pump. This allows the conveyance of excessive conveyed liquid by way of the pumping device through the lubrication region to be avoided, so as to prevent unnecessary wear on the slide bearing and on the shaft by entrained particles in the conveyed liquid.

It may be provided that the rotor is an internal rotor which has one or more permanent magnets which, with respect to the rotation axis, is/are disposed on the radially inward side of the stator.

Alternatively, it may be provided that the rotor is an external rotor which has one or more permanent magnets which, with respect to the rotation axis, are disposed on the radially outward side of the stator.

As has already been mentioned, the electric motor may in particular be an electronically commutated electric motor. Employing the teaching in accordance with the invention, high efficiency may be achieved in the case of an electronically commutated electric motor. This is possible, for example, in that only a slight gap may be provided between the stator and the rotor, so as to enable effective magnetic flow from the stator to the rotor. At the same time, an undesirable accumulation of magnetic particles in the gap may be largely avoided.

The following description of preferred embodiments of the invention in conjunction with the drawing serves in explaining the invention in more detail.

A first preferred exemplary embodiment of a circulating pump in accordance with the invention, which is illustrated in FIG. 1 and shown in cross-section, in its entirety is identified using the reference sign 10. The circulating pump 10 is a heating pump for conveying conveyed liquid, here in particular water.

A housing 12 of the circulating pump 10 comprises a lower housing part 14 and an upper housing part 16 which are interconnected in a sealing manner, for example by way of a screw connection or by way of support by one or a plurality of sealing elements, for example an annular seal 18.

The circulating pump 10, in a receptacle space 20 which is formed between the lower housing part 14 and the upper housing part 16, comprises an electric motor 22 which has a stator 24 and a rotor 26. The stator 24 is positioned on a step 28 which is formed on a lower housing part 14 and in a manner known per se comprises coils which by way of a controller 30 of the electric motor 22 may be loaded with an electric current. The controller 30 is electrically connected to the stator 24 by way of a control line 32 which is only indicated.

The stator 24 is otherwise sealed with respect to the receptacle space 20 by way of a diaphragm 34. The receptacle space 20 is otherwise fluidically filled with the conveyed liquid, here water, with reference being made thereto further below. The diaphragm 34 is clamped on the annular seal 18, so as to be between the housing parts 14 and 16.

The rotor 26 has a shaft 36 which is centrally disposed in the housing 12 and which defines a rotation axis 38. A conveying element 40, presently a impeller 42 which is rotatable about the rotation axis 38, for conveying water is held so as to be rotationally fixed to the shaft 36. The impeller 42 is disposed below an upper housing wall 44 of the upper housing part 16 in the receptacle space 20. In a manner not illustrated, a central through opening 46 in the upper housing wall 44 is connected to a supply line of the circulating pump 10, so that water to be circulated may be supplied thereto. That region above the impeller 42 that faces the through opening 46 corresponds to an intake side 48 of the circulating pump 10.

Water which has been conveyed by means of the impeller 32 may be discharged by the circulating pump 10 by way of a discharge line which is likewise not illustrated in the drawing. A pressurized side 50 of the circulating pump 10 extends in the circumferential direction of the impeller 42 about the rotation axis 38. Circulated water may radially or tangentially exit the housing 12 by way of the discharge line (not shown).

“Axial” and “radial” are here to be understood as being with respect to the rotation axis 38.

As a bearing for the shaft 36, the circulating pump 10 comprises a slide bearing 52. The slide bearing 52, below the impeller 42, in that region of the receptacle space 20 that is bordered by the lower housing part 14, comprises two bearing elements 54 and 56. The bearing elements 54 and 56 are in each case configured as bearing rings 55 and 57 which are mutually spaced apart in the axial direction and which surround the shaft 36 in the circumferential direction.

The bearing rings 55 and 57 are all-solid bearing rings, for example made of graphite. A bearing gap is present between the slide bearing 52 and the shaft 36. A lubrication region 58 in which the slide bearing is liquid-lubricated by means of the conveyed liquid (water) with respect to the shaft 36 is disposed on the bearing gap. This will be referred to in detail subsequently.

The bearing rings 55 and 57 are held on a separator 60 of the circulating pump 10, which has a hollow-cylindrical and sleeve-like portion 62. Facing the impeller 22, the sleeve-like portion 62 transitions into a substantially lid-like portion 64 of the separator 60. The portion 64 in the form of a lid, like the diaphragm 34, is clamped on the annular seal 18 between the housing parts 14 and 16, and is configured so as to be rotationally fixed in relation to the housing 12.

The circulating pump 10, below the bearing ring 57 and axially approximately level with the step 28, has an axial bearing 66 which is held so as to be rotationally fixed on the shaft 36. The axial bearing 66 serves in supporting the rotor 26 in the axial direction, on the one hand. For this purpose, the axial bearing 66 contacts the bearing ring 57 in a planar manner, the axial bearing 66 and the bearing ring 57 thus forming interacting support elements, having support faces for mutual planar support disposed thereon.

On the other hand, the axial bearing 66 also serves in sealing the lubrication region 58, to which reference will be made further below.

The axial bearing 66 is axially adjoined by a rotor space 68 as a portion of the receptacle space 20. The rotor space 68 is of a hollow dome shape and on the lower side is delimited by a lower housing wall 70 of the lower housing part 14. The lower housing wall 70 transitions into the step 28. The diaphragm 34 is disposed in the rotor space 68 and separates a first space region that faces the shaft 36 in a fluid-tight manner from a second space region that faces the housing wall 70.

A magnet mounting 72 of the rotor 26 is connected so as to be rotationally fixed to the shaft 36 in the rotor space 68. The magnet mounting 72 is formed in the shape of a radially widening sleeve, the diameter of which in the region of the stator 24 being larger than in the region of the rotor space 68. Permanent magnets 74 of the rotor 26 are held on the magnet mounting 72. The permanent magnets 74 interact with the alternating magnetic fields which are generated by the stator 24, so as to set the rotor 26 in rotation.

The permanent magnets 74 and that portion of the magnet mounting 72 that holds them extend axially over the length of the stator 24 and from the bearing ring 55 up to the bearing ring 57. The permanent magnets 74 and that portion of the magnet mounting 72 that holds them are positioned radially between the sleeve-like portion 62 and the diaphragm 34.

A gap 76 is disposed between the permanent magnets 74 and the diaphragm 34. The gap 76 is very narrow, for example in the millimeter range or in the sub-millimeter range. The diaphragm 34 and the gap 76 are penetrated by the alternating fields which are generated by the stator 24 and act on the permanent magnets 74. The narrowness of the gap 76 enables a high level of magnetic flux so that the circulating pump 10 has a high degree of efficiency. For this purpose, the electric motor 22 is configured in particular as an electronically commutated electric motor.

As has already been mentioned, the slide bearing 52 in relation to the shaft 36 is liquid-lubricated. The lubrication region 58 is in fluid communication with a conveying space 78 as a portion of the receptacle space 20. The impeller 42 is disposed in the conveying space 78.

In order to achieve effective fluid lubrication, fluid channels are disposed at the lubrication region 58. Said fluid channels may be considered as belonging to a fluid guide 80 of the circulating pump 10 for supplying, transmitting, and discharging conveyed liquid to the lubrication region 58, through the lubrication region 58, and away from the lubrication region 58. The fluid guide 80 comprises at least one and preferably a plurality of fluid channels. The fluid channel(s) are formed between the bearing rings 55 and 57, on the one hand, and the shaft 36, on the other hand, as well as on the axial bearing 66 and in the shaft 36.

A bearing gap between the slide bearing 52 and the shaft 36 may form a fluid channel.

The fluid guide 80 comprises axial fluid channels 82, for example, which are formed between the bearing rings 55 and 57 and the shaft 36 (FIGS. 1 and 2). The fluid channels 82 may be formed by recesses on the bearing rings 55, 57, on that side thereof that faces the shaft 36, for example. The recesses are groove-like, for example, and extend in the axial direction. The fluid channels 82 in the circumferential direction of the rotation axis 38 may extend over a limited angular range. It is also conceivable that the fluid channels 82 are formed axially in portions, as annular channels about the shaft 36. Fluid channels which run in the bearing rings 55 and 57 may also be formed instead of the fluid channels 82.

The fluid channels 82 enable the conveyed liquid to enter into the lubrication region 58 from the conveying space 78 and, on account thereof, to enable effective lubrication between the slide bearing 52 and the shaft 36. The lubrication is advantageous in terms of reduction of wear and dissipation of heat, thus facilitating reliable operation of the circulating pump 10. The fluid guide 80 furthermore comprises at least one and, as is presently the case, preferably a plurality of fluid channels 84. The fluid channels 84 are radial channels which are formed as recesses on the axial bearing 66. The fluid channels 82 on the bearing ring 57 open into the fluid channels 84, so that conveyed liquid may be transported to the fluid channels 84.

Webs which form support elements by way of which the axial bearing 66 abuts on the bearing ring 57 are present in the circumferential direction between the fluid channels 84. An annular region 86 is disposed radially outside the fluid channels 84, on that side that faces away from the shaft 36. The axial bearing 66 on the region 86 has a planar support element for support on the bearing ring 57. The region 86 seals the lubrication region 58 (see below).

Alternatively or additionally to the radial fluid channels 84, there may also be spiral, annular, or part-annular fluid channels present.

A gap between the axial bearing 66 and the slide bearing 52 may be sufficient for lubrication therebetween, without a fluid channel having to be provided on the axial bearing 66 or on the slide bearing 52.

An annular gap 87 is formed between the axial bearing 66 and the portion 62.

As has been mentioned, the fluid guide 80 furthermore comprises fluid channels which are formed in the shaft 36. These fluid channels by way of entry openings 88 open into the fluid channels 82 on the bearing ring 57 and into the fluid channels 84. The entry openings 88 are formed on the external circumference of the shaft 36. Conveyed liquid may enter into the shaft 36 through the entry openings 88 and in said shaft 36 flow axially in the direction of the intake side 48. Facing the intake side 48, exit openings 90 through which the conveyed liquid may exit from the shaft 36 are formed on the shaft 36. The exit openings 90 are disposed on the external circumference of the shaft 36, for example, or on an end side thereof, see FIG. 1.

Overall, effective lubrication on the lubrication region 58 is enabled by the fluid guide 80. Conveyed liquid may be routed from the pressurized side 50 through the fluid channels 82, 84 and through the fluid channels in the shaft 36 up to the intake side 48 of the circulating pump 10. Lubricating is performed between the slide bearing 52 and the shaft 35, as well as between the axial bearing 66 and the slide bearing 52.

The circulating pump 10 comprises a sealing device 92 for sealing the lubrication region 58 with respect to the rotor space 68. The sealing device 92 comprises a sealing element 93 which in the case of the exemplary embodiment shown in FIGS. 1 and 2 is integrally configured by the axial bearing 66. For this purpose, the axial bearing 66 may be made of a ceramics material for example, in particular of aluminum-oxide (Al₂O₃) or carbon silicide (SiC).

The region 86 which is radially outside the fluid channels 84 serves for sealing the lubrication region 58. Interacting axial sealing faces which here extend in the circumferential direction of the rotation axis 38 are formed in this manner between the axial bearing 66 and the bearing ring 57. The axial bearing 66 and the bearing ring 57 in this manner form a mechanical seal 104.

Sealing of the lubrication region 58 with respect to the rotor space 68 need not be perfect here. However, sealing is performed to such an extent that the volumetric flow of the liquid from the lubrication region 58 through the region 86 and the gap 87 to the rotor space 68 is negligible in relation to the volumetric flow through the lubrication region 58, so as to ensure fluid-lubrication at the latter.

Sealing of the lubrication region 58 with respect to the rotor space 68 is here of relevance because the rotor space 58 is in fluid communication with the gap 76 located between the stator 24 and the rotor 26. By way of sealing it may be ensured that no significant fluid flow is formed through the gap 76. This is relevant since the gap 76 is very narrow, as has been mentioned.

By avoiding any significant fluid flow it may be largely prevented that magnetic particles which are entrained in the conveyed liquid can settle on the permanent magnets 74 and, on account thereof, lead to an accumulation in the gap 76. This accumulation which is observed in the previous circulating pumps results in increased friction between the stator and the rotor. The friction leads to undesirable wear, to undesirable generation of heat, to generation of noise and may lead to failure of the circulating pump. Abrasion of the diaphragm 34 is particularly critical, on account of which conveyed liquid may penetrate the electrical portion of the receptacle space 20.

These disadvantages may be avoided by the configuration of the circulating pump 10 in accordance with the invention, in which the lubrication region 58 is sealed with respect to the rotor space 68 and thus to the gap 76.

Furthermore, substantially fluid-tight sealing of the gap 76 with respect to the conveying space 78 is performed by way of the separator 60. The lid-like portion 64 of the separator 60 in particular covers the conveying space 78 in the direction of the gap 76 in a substantially fluid-tight manner. Moreover, substantially fluid-tight sealing of the lubrication region 58 with respect to the magnet mounting 72 is performed by way of the sleeve-like portion 62. This is furthermore performed by way of sealing between the axial bearing 66 and the bearing ring 57.

The gap 76 and the rotor space 68 which are in mutual fluid communication are nevertheless filled with conveyed liquid. In small amounts, conveyed liquid may enter from the lubrication region 58 past the sealing device 92 via the gap 87 into the rotor space 68 and into the gap 76. However, this volumetric flow is negligible in comparison with the volumetric flow through the lubrication region 58.

The provision of conveyed liquid in the gap 76 enables dissipation of heat, for example.

FIGS. 3 and 4 partially show further exemplary embodiments (reference signs 140 and 150, respectively) of a circulating pump in accordance with the invention, in an illustration which corresponds to the circulating pump 10 of FIG. 2. In a sectional view, FIG. 5 shows a preferred exemplary embodiment of a circulating pump which in its entirety is identified by the reference sign 94.

Same features and components or features and components with the same function of the circulating pump 10 on the one hand, and of the circulating pump 94 and of the circulating pumps 140 and 150, respectively, which are shown in detail, on the other hand, are identified by the same reference signs. The abovementioned advantages of the circulating pump 10 may likewise be achieved with the other circulating pumps 140, 150, and 94, so that reference may be made in this context to the preceding explanations.

In the exemplary embodiment 140 illustrated in FIG. 3, the sealing device 92, differing from the circulating pump 10, is not integrally formed with the axial bearing 66.

Instead, the axial bearing and a sealing element 98 of the sealing device 92 are in two parts in the case of the exemplary embodiment 140 in accordance with FIG. 3. The axial bearing 66 forms a support element 96 which is axially spaced apart from the bearing ring 57. The sealing element 98 of the sealing device 92 is disposed between the support element 96 and the bearing ring 57. The sealing element 98 is of annular form and connected thereto and forms the sealing region 86. This connection is performed on mutually adjacent axial contact faces by way of which the support element 96 bears on the sealing element 98 in a planar manner and may be supported thereon.

The fluid channels 84 are formed radially inward with respect to the sealing element 98, so as to ensure liquid lubrication with respect to the bearing ring 57. The webs between the fluid channels 84 enable support of the axial bearing 66 on the bearing ring 57.

In the exemplary embodiment 150 in accordance with FIG. 4, the axial bearing 66 on the external circumference has a recess in the shape of an encircling annular groove 100. The sealing device 92 has a sealing element in the shape of an O-ring 102 which is inserted in the annular groove 100. Sealing of the lubrication region 58 with respect to the rotor space 68 is performed with respect to the sleeve-like portion 62. In particular, the sealing faces extend on the external circumference of the axial bearing 66 and on the internal circumference of the sleeve-like portion 62.

In addition, the fluid channels 84 are formed on the axial bearing 66, and the axial bearing 66 may be supported on the bearing ring 57 by way of the webs between the fluid channels 84.

The circulating pump 10 comprises the electric motor 22 which is a so-called “internal rotor” motor. In an internal rotor motor, the permanent magnets 74 with respect to the stator 24 are disposed so as to be radially inside. By contrast, the circulating pump 94 comprises the electric motor 22 which in this exemplary embodiment is configured as a so-called “external rotor” motor. In an external rotor motor the permanent magnets 74 are positioned radially outside the stator 24 and revolve around the latter as the rotor 26 rotates.

The stator 24 in the circulating pump 94 is held on the separator 60 and fastened to the external side thereof which faces away from the slide bearing 52. The diaphragm 34 seals the stator 24 in the direction of the rotor space 68 and of the gap 76. Sealing of the stator in the direction of the conveying space 78 is ensured by the lid-like portion 64 of the separator 60.

Sealing of the lubrication region 58 with respect to the gap 76 in the circulating pump 94 is performed in the same manner by means of the axial bearing 66 which integrally forms the sealing element 93 of the sealing device 92, corresponding to the exemplary embodiment illustrated in FIGS. 1 and 2. Of course, sealing of the lubrication region 58 with respect to the rotor space 68 could be performed as in the exemplary embodiments in accordance with FIG. 3 or 4 in further exemplary embodiments in which an electric motor 22 with an external rotor motor is employed.

In the exemplary embodiments of the circulating pump in accordance with the invention in FIGS. 1 and 2, the sealing device 92 is designed as a mechanical seal 104. The bearing ring 57 which is held so as to be rotationally fixed to the separator 60 acts as the sliding ring and contacts the counter ring in the shape of the axial bearing 66 in a sealing manner.

FIG. 6 in a manner corresponding to FIG. 2 shows in portions a further advantageous exemplary embodiment of a circulating pump in accordance with the invention (reference sign 160). The construction shown in FIG. 6 could be employed in a circulating pump having an internal rotor, in accordance with FIG. 1, or having an external rotor, in accordance with FIG. 5.

Identical reference signs are used for the same features and components or for features and components with the same function.

In the circulating pump 160 in accordance with FIG. 6, the fluid channels 84 extend in the radial direction over the entire width of the axial bearing 66. The fluid guide 58 thus also extends into the fluid channels 84, so that the axial bearing 66 with respect to the bearing ring 57 may be effectively lubricated.

The sealing device 92 is disposed on that side of the axial bearing 66 that is opposite the slide bearing 52 and comprises a mechanical seal 104. A sliding ring 106 which is held so as to be rotationally fixed on the sleeve-like portion 62 and is thus rotationally fixed in relation to the stator 24 is provided. A sealing element, for example in the shape of an O-ring 108, seals between the sliding ring 106 and the portion 62.

The sliding ring 106 is supported on a counter ring 110 which is connected so as to be rotationally fixed to the shaft 36. The sliding ring 106 and the counter ring 110 are sealing elements 112, 114 of the mechanical seal 104. The interacting sealing faces thereof allow the lubrication region 58 to be sealed with respect to the rotor space 68. Conveyed liquid which flows out of the lubrication region 58 through the gap 87 into the space between the axial bearing 66 and the mechanical seal 104 may thus be largely prevented from entering into the rotor space 68. As is the case with the circulating pump 10, it is however also possible that conveyed liquid in small amounts may enter the rotor space 68, so that the latter is likewise filled with liquid.

A ring 116 is furthermore held so as to be rotationally fixed on the portion 62. The ring 116 forms a support element on which an elastic element 118 may be supported. The elastic element 118 in turn is supported on the sliding ring 106, so that the sliding ring 106 by way of the elastic element 118 is subjected to a force which acts on the counter ring 110. The elastic element 118 is a corrugated spring or a corrugated spring pack, for example.

In the previous advantageous exemplary embodiments of the circulating pump, the conveyed liquid flows from the pressurized side 50 of the circulating pump to the intake side 48, so that the conveyed liquid initially flows through the bearing gap between the slide bearing 52 and the shaft 36 and subsequently through the shaft 36 to the intake side 48.

FIG. 7 shows a further preferred exemplary embodiment of a circulating pump in accordance with the invention in which the flow direction of the conveyed liquid through the lubrication region 58 is reversed. A construction of this type may also be employed in the advantageous exemplary embodiments 140, 150, 94, 160 of FIGS. 3, 4, 5, and 6.

The circulating pump shown in FIG. 7 in its entirety is identified by the reference sign 120. Identical reference signs are also used in this case for the same features and components or features and components with the same function.

A central fluid channel 122 is provided in the shaft 36 in the circulating pump 120. The exit openings 90 are omitted. Instead, the fluid channel 122 with respect to the intake side 48 is closed off by a closure element 124. The closure element 124 is a plug which is press-fitted in the fluid channel 122, for example.

An entry channel 126 is formed in the shaft 36 on the pressurized side in the conveying space 78 on the side which faces the slide bearing 52. The conveying space 78 by way of the entry channel 126 opens into the shaft 36. An element 128 which is connected so as to be rotationally fixed to the shaft 36 is disposed in the conveying space 78, close to the entry channel 126. The element 128 is designed in the form of a disk, for example. As the element 128 rotates, a friction pump is formed in combination with the bearing ring 55 in the conveying space 78. Conveyed liquid is pumped by way of the entry channel 126 into the fluid channel 122.

A filter element 130 is disposed in the fluid channel 122. The filter element 130 is held in the fluid channel 122 by way of a press-fit, for example. The filter element 130 may in particular be a sinter filter.

Fluid communication between the fluid channel 122 and the lubrication region 58 on the fluid channels 84 is provided by way of exit channels 132. Conveyed liquid may be conveyed through the fluid channel 122 via the exit channels 132 into the fluid channels 84 and 82. Particles which are present in the conveyed liquid are filtered by the filter element 130, so that said particles cannot enter into the lubrication region 58. The accumulation of particles in the lubrication region 58 is avoided on account thereof. This has a favorable effect on the bearing of the shaft 36 and on the fluid lubrication on the lubrication region 58.

It is furthermore advantageous that the amount of conveyed liquid depends on the sizing of the friction pump between the slide bearing 52 and the element 128, and is thus substantially independent of the operating point of the circulating pump 120. Unnecessary wear on the slide bearing 52 and on the shaft 36 by conjointly conveyed particles and excessive clogging of the filter element 130 is avoided on account thereof.

LIST OF REFERENCE NUMERALS

-   10 Circulating pump -   12 Housing -   14 Lower housing part -   16 Upper housing part -   18 Annular seal -   20 Receptacle space -   22 Electric motor -   24 Stator -   26 Rotor -   28 Step -   30 Controller -   32 Control line -   34 Diaphragm -   36 Shaft -   38 Rotation axis -   40 Conveying element -   42 Impeller -   44 Upper housing wall -   46 Through opening -   48 Intake side -   50 Pressurized side -   52 Slide bearing -   54 Bearing element -   55 Bearing ring -   56 Bearing element -   57 Bearing ring -   58 Lubrication region -   60 Separator -   62 Sleeve-like portion -   64 Lid-like portion -   66 Axial bearing -   68 Rotor space -   70 Lower housing wall -   72 Magnet mounting -   74 Permanent magnets -   76 Gap -   78 Conveying space -   80 Fluid guide -   82 Fluid channel -   84 Fluid channel -   86 Region -   87 Gap -   88 Entry opening -   90 Exit openings -   92 Sealing device -   93 Sealing element -   94 Circulating pump -   96 Support element -   98 Sealing element -   100 Annular groove -   102 O-ring -   104 Mechanical seal -   106 Sliding ring -   108 O-ring -   110 Counter ring -   112 Sealing element -   114 Sealing element -   116 Ring -   118 Elastic element -   120 Circulating pump -   122 Fluid channel -   124 Closure element -   126 Entry channel -   128 Element -   130 Filter element -   132 Exit channel -   140 Circulating pump -   150 Circulating pump -   160 Circulating pump 

What is claimed is:
 1. A circulating pump comprising a conveying element for conveying a conveyed liquid, and an electric motor which has a stator, a rotor, and a gap disposed therebetween, the rotor including a shaft rotatable about a rotation axis, the conveying element rotationally fixed to the shaft, the shaft mounted to the circulating pump via a radial slide bearing with a lubrication region configured to be liquid-lubricated with the conveyed liquid, the circulating pump including a sealing device configured to inhibit fluid communication between the lubrication region and the gap located between the stator and the rotor.
 2. The circulating pump in accordance with claim 1, wherein the circulating pump comprises a fluid guide which, for supplying, transmitting, or discharging conveyed liquid into, through, or from the lubrication region has at least one fluid channel which allows conveyed liquid to flow therethrough.
 3. The circulating pump in accordance with claim 2, wherein a fluid channel by way of at least one entry opening is in fluid communication with a pressurized side or an intake side of the circulating pump and/or wherein a fluid channel by way of at least one exit opening is in fluid communication with a pressurized side or an intake side of the circulating pump.
 4. The circulating pump in accordance with claim 1, further comprising one of: (a) at least one fluid channel for the conveyed liquid disposed at the lubrication region, (b) a fluid guide having the at least one fluid channel for conveyed liquid, and a combination of (a) and (b).
 5. The circulating pump in accordance with claim 4, wherein said at least one fluid channel is formed in the slide bearing or in the shaft.
 6. The circulating pump in accordance with claim 4, wherein said at least one fluid channel is disposed between the slide bearing and the shaft.
 7. The circulating pump in accordance with claim 4, wherein the shaft has at least one entry opening or exit opening configured to permit the conveyed liquid to enter into the shaft or exit therefrom, respectively.
 8. The circulating pump in accordance with claim 4, wherein said at least one fluid channel runs axially with respect to the rotation axis.
 9. The circulating pump in accordance with claim 4, wherein said at least one fluid channel is configured as an annular channel or as a partial annular channel in a circumferential direction of the rotation axis.
 10. The circulating pump in accordance with claim 4, wherein said at least one fluid channel is configured as a radial channel with respect to the rotation axis.
 11. The circulating pump in accordance with claim 4, wherein a filter element for filtering the conveyed liquid is disposed in said at least one fluid channel.
 12. The circulating pump in accordance with claim 1, wherein the circulating pump comprises an axial bearing for supporting the rotor against axial movement relative to the stator.
 13. The circulating pump in accordance with claim 12, wherein the axial bearing is axially supported on the slide bearing.
 14. The circulating pump in accordance with claim 12, wherein at least one fluid channel is disposed on the axial bearing.
 15. The circulating pump in accordance with claim 12, wherein the axial bearing is rotationally fixed to the shaft.
 16. The circulating pump in accordance with claim 12, wherein a sealing element of the sealing device is disposed on the axial bearing.
 17. The circulating pump in accordance with claim 12, wherein a sealing element of the sealing device is axially positioned between the axial bearing and the slide bearing.
 18. The circulating pump in accordance with claim 12, wherein the axial bearing forms an axial support element for a sealing element of the sealing device.
 19. The circulating pump in accordance with claim 12, wherein a sealing element of the sealing device is integral with the axial bearing.
 20. The circulating pump in accordance with claim 12, wherein a sealing element of the sealing device is separate from the axial bearing.
 21. The circulating pump in accordance with claim 20, wherein a sealing element of the sealing device is connected to the axial bearing.
 22. The circulating pump in accordance with claim 12, wherein a sealing element of the sealing device, at least in portions, surrounds the axial bearing in a circumferential direction of the rotation axis.
 23. The circulating pump in accordance with claim 12, wherein the sealing device is disposed on a side of the axial bearing that is opposite the slide bearing.
 24. The circulating pump in accordance with claim 1, wherein the sealing device comprises or forms a mechanical seal having a sliding ring rotationally fixed in relation to the stator, and having a counter ring rotationally fixed to the shaft.
 25. The circulating pump in accordance with claim 24, wherein the sliding ring is formed by the slide bearing, and wherein the counter ring is formed by an axial bearing of the circulating pump.
 26. The circulating pump in accordance with claim 24, wherein the sliding ring and the counter ring are mutually biased towards each other by a biasing element.
 27. The circulating pump in accordance with claim 1, wherein a sealing element of the sealing device has a substantially annular or disk-like configuration and is disposed in a plane perpendicular to the rotation axis.
 28. The circulating pump in accordance with claim 1, wherein the circulating pump has a separator which separates the lubrication region from the gap located between the stator and the rotor, wherein the separator is, at least in portions, disposed between the shaft and the gap in a radial direction with respect to the rotation axis.
 29. The circulating pump in accordance with claim 28, wherein the separator comprises or forms a cover which covers a conveying space of the circulating pump in which the conveying element is disposed in relation to the gap located between the stator and the rotor.
 30. The circulating pump in accordance with claim 28, wherein the slide bearing is disposed on the separator.
 31. The circulating pump in accordance with claim 28, wherein the separator is rotationally fixed with respect to the stator.
 32. The circulating pump in accordance with claim 1, wherein a rotor space which is sealed by the sealing device in relation to the lubrication region adjoins the lubrication region in an axial direction.
 33. The circulating pump in accordance with claim 32, wherein the rotor space is in fluid communication with the gap located between the stator and the rotor.
 34. The circulating pump in accordance with claim 32, wherein the shaft axially engages through the sealing device, the rotor has a magnet mounting rotationally fixed to the shaft in the rotor space, and at least one permanent magnet of the electric motor is disposed on said magnet mounting.
 35. The circulating pump in accordance with claim 1, wherein the circulating pump comprises a pumping device for conveying the conveyed liquid through the lubrication region.
 36. The circulating pump in accordance with claim 35, wherein the amount of conveyed liquid conveyed by the pumping device is independent or substantially independent of an operating point of the circulating pump.
 37. The circulating pump in accordance with claim 1, wherein the rotor is an internal rotor having one or more permanent magnets disposed on a radially inward side of the stator relative to the rotation axis.
 38. The circulating pump in accordance with claim 1, wherein the rotor is an external rotor having one or more permanent magnets disposed on a radially outward side of the stator relative to the rotation axis.
 39. The circulating pump in accordance with claim 1, wherein the electric motor is an electronically commutated electric motor. 